Engineering Experience 4: Design a Small Solar Vehicle/Nl/2014: Team PM9

Sol Invictus

Welcome on the wikipage of 'Sol Invictus'. This team will participate in the small solar vehicle (SSV) race at the Martyrs Square on Tuesday 13/05. On this page we will keep you informed about the progress of the project.

Team Members

Our team consists of six members, each student industrial electromechanical engineering at GroepT Leuven. Sol Invictus, or unconquerable sun is an ancient Roman term that was linked to the divine and imperial.

Member	Function
Adriaan Buntinx	Teamleader,Design
Wannes de Bruyn	Mechanics
Charles Colin	Programmer
Stijn Lenaerts	Material management
Wouter Meijers	Drawing

EE4: Design of a solar car

Context

The central theme of the Engineering Experience 4 - project is “Make stuff work”. Different teams of students design and build a ‘Small Solar Vehicle’ (SSV). Each team receives a solar panel and a DC-motor at their disposal. The Vehicle is also subjected to a number of tests and its behaviour is predicted, at first using manual calculations; later using simulation software. In the end, every SSV will take part in a “solar-race”. Moreover, additional grades can be gained in following categories: - most innovative vehicle, - most beautiful vehicle. Next, the team performs a critical analysis on the SSV. The analysis is carried out in the following fields: aerodynamics, dynamics, strength of materials, material science, mathematics and energy.

The whole idea behind this project is that the team works as an engineering office in service of the solar vehicle team and have to design a miniature of their solar car to bring on the market. This to gain some additional budget.

Race

The SSV must not only be energetically optimal but should also participate in a race at the Martyrs Square on Tuesday 13/05. The SSV gets 10 m run, after which it collides with a petanqueball of (710 ± 10)g. This ball is on a ramp and the aim is to get the ball as high as possible. There are always three teams racing against each other because the solar energy is not always the same. Other rules and restrictions can be found in the competition rules.

Blog

WEEK 1

We got our first seminar in which the project was explained. The students were divided into teams, a coach was assigned and we already started on the first assignments: collaboration contract, Plan of Approach, Work Breakdown Structure and our Gantt Chart. These tasks were divided under the team members and we came together in the middle of the week to evaluate and complement each other’s work. Further, a teamname was chosen, a person was employed to make the teamlogo and this wikipage was crated.

WEEK 2

This week we got a seminar about how we could determine our solar panel characteristics and how a DC motor works. After this seminar we received our solar panel and DC-motor and had to make the measurements needed to final determine the diode factor of our solar panel. These measurements were carried out under a bright lamp and consist of defining the current and voltage when subjected to an adjustable resistor. Out of these measurements we had to make a I-U graph, from which we had to define our maximal power. An appropriate error analysis was needed to determine the final error on the measurements of the characteristic. We had our first feedback moment with our coach. Because of a misunderstanding when uploading our wikipage, our files were not yet visible. As we were correct with the deadline, no sanctions were taken and we will get our feedback in the next session.

WEEK 3

Week 3 was all about race strategy. We were put in the situation of the race, while the real stuff was being explained. A final explanation about the DC-motor and the solar panel, an explanation of the gear ratio, the main influences on the SSV during the race and the beginning of Matlab. We could say the project really started this week. The ideas we had we could finally put in a more realistic context, thus eliminate all the ones that were a bit far-fetched. Also we had to start with Matlab, a complicated program that would allow us to modellise difficult equations.

WEEK 4

This week an important part of Matlab was explained, namely Simulink. Quickly explained, Simulink offers you the possibility to create a system as close as possible to your SSV, while Matlab does the maths. We will be able to get very precise information on how our car will react to mass, gear ratio, form of the car and so on. We also discussed ways to make the car generate energy that could be lost. You see, when the car reaches maximum velocity, energy is 'lost' in a way because your DC-motor does not give momentum anymore. It's sole job at that point is to keep the velocity constant, while a lot of possible momentum is not used. This problem has to answers: or you store some energy using for instance a spring, or you try to make your SSV reach its peak velocity just before the moment of impact. For the fisrt case, we thoufht about elastics that could pull back a balk, or a spring and so on. For the second case using different gears seemed a good way to reach a high velocity, just like normal cars have to change gears.

WEEK 5

Week 5 was a very full week. We had to start using Matlab and Simulink in an effective way. To do so, our gear ratio and ideal mass had to be found. This we did using Matlab. Simulink will be for next week, using the information found this week. We are also working hard on our SSV Case l, a document we will have to submit Friday next week. A lot of questions have to be answered, and many difficult mathematical equations have to be solved. We are using the bissection method to find intersections that we will use later. On an other side, our team member Loïc Massart left us because it seemed he wasn't allowed to participate at the EE4 project. While he will be missed, we cannot let us down because there is still a lot of work to do due for next week Friday.

WEEK 6

Final week before the deadline and still a lot to do. That's why we decided to come together more often. We're experiencing a very difficult deadline and the last things are finally put together to have a decent (if not very good) SSV Case l to submit at the end of the week. Construction is about to begin seeing all the math and theorethical work is almost done. Time to build something!

WEEK 7

We got our Case 1 back from our mentor. Some things have to be changed but the overall result was satisfying. But our next goal is Case 2 and the construction of the SSV. We're gathering the elements of the car and finishing the drawings and so on. We are also preparing ourselves for the intermediate test next week. It will be about the DC motor and technical drawings.

WEEK 8

This week we had not much time to concentrate on the project because of the test. We all spent some time at home or in the library because of the amount of information we have to know for the test.

EASTER HOLIDAY

During the Easter holiday, the whole team went to the Fablab in Heverlee to start building the SSV. We sawed aluminium bars, made bearings to ensure a good roll of the axes using a 3D-printer, drilled holes and so further and so on. At the end of the day, we had achieved the basis of our SSV, which is extremely sturdy and likely to resist whatever the impact will be. Adriaan took it home to continue working on the gears and the wheels.

The SSV of team PM9

Our Gear Box

WEEK 9

This week we went to the parking of GroupT where the track had been built. We were given the opportunity to test our car and see how hard it hit. We used a Piëzoelectronics device to calculate the force developped by our SSV from a small distance. We then went upstairs to work on Case II, which should be done for Friday 9th of May. Important deadline indeed!

WEEK 10

We tested our ssv to see if the gear ratio was ok and if the bearings where doing their work. We worked a bit more on Case II and noticed some small problems due to a faulty test during week 9. Case II might not be as complete as we would like it to be.

WEEK 11

Case II was finished a bit in a hurry but everything finally assembled together. We tested our SSV on a petanqueball and were delighted to see it hit the ball really hard, when other teams had difficulties with just letting their SSV's ride. We think we might have to change some things when we'll get our Case II back. But those worries are for next week.

WEEK 12

Because of the bad weather, the race was postponed to next week. This is a pity, but a SSV does not function quite good under the rain. We had the opportunity to show our SSV to the other teams and to go and take a look at the other SSV's. It's a shame we did not win a price that day.

WEEK 13

On Thuesday 20th May, we went down with our SSV to the Martelarenplein in front of Leuven's station to race against the other teams. Our SSv worked quit well and there was a lot of sun. We soon discovered we were in a very strong poule where the resluts where skyhigh. We regrettably got stuck in our poule. This was a bit annoying, because if we had been in poule 1, we would've gotten to to semi-finals, which we didn't. We managed to get the ball to a height of 9.6, 0.6 and 10.4. The 0.6 happened because the SSV hit the part on which the ball was resting, giving nearly no force to the ball. We thus upgraded our SSV a bit buy making the impactingpart a bit longer and by setting it on a higher height. Because we were neck and neck with two other teams at the end of our poule, we competed against them once more, but PM8 got the better hand. The race on itself was very interesting and we saw a lot of very good SSV's on the tracks. in the end it was the SSV from PM 10 who won the race, which we congratulate them for, breaking on the way the record of height a ball achieved to reach.